As is known, hollow glass articles are formed in aligned, adjacent molds, and, once molded, are extracted from the respective molds and placed on a supporting surface, from which they are subsequently transferred onto a linear conveyor which feeds them successively to an output of the system.
The glass articles are transferred from the supporting surface to the linear conveyor by means of transfer units, each of which comprises a pickup member for engaging one or more articles to be transferred; a pneumatic linear actuator for moving the pickup member horizontally to and from the glass articles; and an angular actuator, normally defined by an electric motor, for rotating the linear actuator and the pickup member, about a vertical hinge axis, between a pickup position, to pick the articles off the supporting surface, and a release position, to release the articles onto the linear conveyor.
With the increase in the output rate of molding systems, known transfer units of the type described above have proved increasingly unsatisfactory and unreliable. This is mainly due to the presence of pneumatic actuators, which fail to provide for precise, repeat control of the position and travelling trajectory of the pickup member, which is essential for preventing damage to the articles, particularly when, again for reasons of output rate, the articles must be transferred at relatively high speed onto the conveyor to form two parallel lines of articles. Unlike single-file positioning, two-line positioning on the conveyor belt calls for at least one dedicated transfer unit differing in size and construction from the other units.
Regardless of construction characteristics, known transfer units invariably comprise at least one pneumatic actuator located above the surface supporting the articles for transfer, adjacent to the articles themselves, and therefore operating in a hot environment, so that the units call for continual, constant routine maintenance.